The objectives of this proposal are to: (1) identify the prevalence of sleep apnea (SA) in women and its relationship to age; (2) predict those women at risk for SA; and (3) define the natural history of those with SA. Often SA is accompanied by considerable morbidity; the associated excessive daytime sleepiness, cardiovascular abnormalities and cognitive impairment impact greatly on daytime functioning. The obese, hypertensives, elderly and postmenopausal women are reported to be at increased risk for SA. We have published on the prevalence of SA in several special populations: elderly subjects without sleep complaints and insomniac, narcoleptic, hypertensive and obese patients. We are currently establishing the prevalence of SA in men based on the sleep laboratory evaluation of approximately 1,000 men randomly selected from a randomly generated telephone sample of 4,364 men from the general population. To date we have completed the first-stage telephone survey and have recorded in the sleep laboratory about 700 for the second stage of the study. Our preliminary estimate of prevalence is that about 2.2% of the adult male population have clinically diagnosable SA. Further, in the male sample, the age distribution is not linearly related to age. Rather, it peaks at approximately age 55. Finally, the major risk factors appear to be obesity and snoring. The differences in the male/female ratio in clinical and selected populations range from 10.0:1 to 1.9:1. One recent study suggests that the prevalence of SA in women is about 2-fold less than in men. However, this study did not sample the general population and used only a restricted age range (30 to 60 years) which did not allow the assessment of the influence of menopause. Thus, the prevalence of SA in women in the general population remains largely undetermined. In order to establish the prevalence in women with reasonable precision, the proposed prevalence determination will employ a two-stage sample modified from our prevalence study in men currently in progress in the following two ways: 1) an expanded telephone sample (N=12,000 women) selected randomly from the general population will be evaluated, for clinically relevant risk factors for SA; and 2) a second sample (N=1,500) selected randomly from the first sample based on higher risk for SA (including the additional risk factor of menopause) will be evaluated in the sleep laboratory to determine the presence of SA. This strategy will yield an adequate power in order to establish the prevalence of SA requiring treatment and SDB in women in the general population as well as result in a large enough sample to enable us to establish the association between risk factors and SA in women.